Date: Wed, 20 Jun 2012 08:02:44 +0000 (UTC) From: "Andrey V. Elsukov" <ae@FreeBSD.org> To: src-committers@freebsd.org, svn-src-user@freebsd.org Subject: svn commit: r237293 - user/ae/bootcode/sys/boot/i386/pmbr Message-ID: <201206200802.q5K82iRG027818@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: ae Date: Wed Jun 20 08:02:44 2012 New Revision: 237293 URL: http://svn.freebsd.org/changeset/base/237293 Log: Teach PMBR boot code read the backup GPT header and skip GEOM's metadata. Submitted by: hrs Modified: user/ae/bootcode/sys/boot/i386/pmbr/pmbr.s Modified: user/ae/bootcode/sys/boot/i386/pmbr/pmbr.s ============================================================================== --- user/ae/bootcode/sys/boot/i386/pmbr/pmbr.s Wed Jun 20 07:56:38 2012 (r237292) +++ user/ae/bootcode/sys/boot/i386/pmbr/pmbr.s Wed Jun 20 08:02:44 2012 (r237293) @@ -42,8 +42,9 @@ .set STACK,EXEC+SECSIZE*4 # Stack address .set GPT_ADDR,STACK # GPT header address .set GPT_SIG,0 - .set GPT_SIG_0,0x20494645 - .set GPT_SIG_1,0x54524150 + .set GPT_SIG_0,0x20494645 # "EFI " + .set GPT_SIG_1,0x54524150 # "PART" + .set GEOM_MAGIC,0x4d4f4547 # "GEOM" .set GPT_MYLBA,24 .set GPT_PART_LBA,72 .set GPT_NPART,80 @@ -52,6 +53,8 @@ .set PART_TYPE,0 .set PART_START_LBA,32 .set PART_END_LBA,40 + .set DPBUF,PART_ADDR+SECSIZE + .set DPBUF_SEC,0x10 # Number of sectors .set NHRDRV,0x475 # Number of hard drives @@ -91,15 +94,39 @@ main: cmpb $0x80,%dl # Drive valid? jb main.2 # Yes main.1: movb $0x80,%dl # Assume drive 0x80 # -# Load the primary GPT header from LBA 1 and verify signature. -# -main.2: movw $GPT_ADDR,%bx +# Load the GPT header and verify signature. Try LBA 1 for the primary one and +# the last LBA for the backup if it is broken. Skip the LBAs if GEOM +# metadata found at the backup location. +# +main.2: call getdrvparams # Read drive parameters + movb $1,%dh # %dh := 1 (reading primary) +main.2a: movw $GPT_ADDR,%bx movw $lba,%si - call read + call read # Read header and check GPT sig cmpl $GPT_SIG_0,GPT_ADDR+GPT_SIG - jnz err_pt + jnz main.2b cmpl $GPT_SIG_1,GPT_ADDR+GPT_SIG+4 - jnz err_pt + jnz main.2b + jmp load_part +main.2b: cmpb $1,%dh # Reading primary? + je main.3 # Try backup if yes + cmpl $GEOM_MAGIC,GPT_ADDR # GEOM sig at backup location? + jz main.3 # Skip GEOM metadata + jmp err_pt # Invalid table found +# +# Try alternative LBAs from the last sector for the GPT header. +# +main.3: movb $0,%dh # %dh := 0 (reading backup) + movw $DPBUF+DPBUF_SEC,%si # %si = last sector + 1 + movw $lba,%di # %di = $lba + cmpl $0,(%si) # + jnz main.3a # + decl 0x4(%si) # 0x4(%si) = last sec (32-64) +main.3a: decl (%si) # 0x0(%si) = last sec (0-31) + movw $2,%cx + rep + movsw # $lastsec--, copy it to $lba + jmp main.2a # Read the next sector # # Load a partition table sector from disk and look for a FreeBSD boot # partition. @@ -172,6 +199,16 @@ read: pushl 0x4(%si) # Set the LBA jc err_rd # If error ret # +# Check the number of LBAs on the drive index %dx. Trashes %ax and %si. +# +getdrvparams: + movw $DPBUF,%si # Set the address of result buf + movw $0x001e,(%si) # len + movw $0x4800,%ax # BIOS: Read Drive Parameters + int $0x13 # Call the BIOS + jc err_rd # "I/O error" if error + ret +# # Various error message entry points. # err_big: movw $msg_big,%si # "Boot loader too
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201206200802.q5K82iRG027818>